The number of people with mood disorders such as major depressive disorder, and exhibiting various symptoms of depressions is increasing every year for numerous reasons such as social stress, unemployment, disease, and poverty. Depression is a major social problem throughout the world. For example, in Japan the occurrence rate of depression in the generation older than 65 years is 5% or more, including major depressive disorder. Some of the depression in this population is associated with mental disturbances representing senile diseases associated with dementia and neurosis. Many depressed patients show high recurrence rate, and severe depressive symptoms are major causes of suicide and drug abuse (Nishimura Ken, “NIPPON RONEN IGAKUZASSHI”, Vol. 33, pp 503-504 (1996)).
Since the period of 1950, tricyclic antidepressant drugs (e.g., imipramine, desipramine, amitriptyline, etc.) have been developed that act to inhibit monoamine reuptake. They are frequently used for treating patients suffering from mood disorders, such as depression and major depressive disorder. However, these drugs have side-effects such as the following: dry mouth, hazy eyes, dysuria, constipation, recognition disturbance and the like due to anticholinergic activity; cardiovascular side-effects such as, orthostatic hypotension, tachycardia and the like on the basis of α1-adrenoreceptor antagonist activity; side-effects such as, sedation, increase in the body weight and the like on the basis of histamine-H1 receptor antagonist activity.
Since 1980, serotonin reuptake inhibitors have been developed, including but not limited to fluoxetine, duloxetine, venlafaxine, milnacipran, citalopram, escitalopram, fluvoxamine, paroxetine and sertraline, and these inhibitors have side-effects such as recognition disturbance, sleep disturbance, and excerbation of anxiety and agitation. Additionally, these inhibitors also have other side effects in the digestive organs, such as nausea, vomiting and the like.
For the reason that the mood disorders such as depressive symptoms, depression and the like are diseases with severely strong psychalgalia, the manifestation of new symptoms on the basis of these side-effects are quite serious problems in the therapy of mood disorders (Shioe Kunihiko, Kariya Tetsuhiko, “SHINKEI SEISHIN YAKURI”, Vol. 11, pp 37-48 (1989); Yamada Mitsuhiko, Ueshima Kunitoshi, “RINSHOU SEISHIN YAKURI”, Vol. 1, pp 355-363 (1998)).
Although the mood disorders including depression and major depressive disorder are heterogeneous diseases, and the causes of these diseases are not been fully understood, it is likely that the abnormalities of monoaminergic central nervous system caused by serotonin, norepinephrine and dopamine and the like, and the abnormality of various hormones and peptides as well as various stressors are causes of depression and various mood disorders (Kubota Masaharu et al., “RINSHOU SEISHIN IGAKU”, Vol. 29, pp 891-899 (2000)). For these reasons, even though antidepressant drugs, such as tricyclic antidepressants and serotonin reuptake inhibitors were used, these drugs are not always effective in treating all depressed patients. About 30% of the depressed patients do not respond to the primarily selected antidepressants (Nelson, J. C, et al., J. Clin. Psychiatry, 55, pp 12-19 (1994)). Further, when a second or third antidepressant is administered to these patients, insufficient improvements of the symptoms occurs in about 10% of these patients (Inoeu Takeshi, Koyama Tsukasa, “RINSHOU SEISHIN IGAKU”, Vol. 38, pp 868-870 (1996)). These patients are called as refractory depression patients.
In some cases, electric shock therapy is used to treat refractory depression, and the efficacy of this treatment has been reported. However, in fact, the condition of numerous patients is not improved (Inoue Takeshi, Koyama Tsukasa, “RINSHOU SEISHIN YAKURI”, Vol. 2, pp 979-984 (1999)). Additionally, psychological anguish experienced by these patients and their families concerning the use of the electric shock therapy can be severe.
New therapeutic trials involve proposed combined therapies using an atypical antipsychotic drug, such as olanzapine, which is an agent for treating for schizophrenia (antipsychotic drug), together with an antidepressant drug such as serotonin reuptake inhibitor (EP 0 367 141, WO 98/11897, WO99/61027, WO99/62522, U.S. 2002/0123490A1 and the like). However, commercially available atypical antipsychotic drugs have significant problems relating to their safety. For example, clozapine, olanzapine and quetiapine increase body weight and enhance the risk of diabetes mellitus (Newcomer, J. W. (Supervised Translated by Aoba Anri), “RINSHOU SEISHIN YAKURI”, Vol. 5, pp 911-925 (2002); Haupt, D. W. and Newcomer, J. W (Translated by Fuji Yasuo and Misawa Fuminari), “RINSHOU SEISHIN YAKURI”, Vol. 5, pp 1063-1082 (2002)). In fact, urgent safety alerts have been issued in Japan relating to hyperglycemia, diabetic ketoacidosis and diabetic coma caused by olanzapine and quetiapine, indicating that these drugs were subjected to dosage contraindication to the patients with diabetes mellitus and patients having anamnesis of diabetes mellitus. Risperidone causes increases serum prolactin levels and produces extrapyramidal side effects at high dosages. Ziprasidone enhances the risk of severe arrhythmia on the basis of cardio-QTc prolongation action. Further, clozapine induces agranulocytosis, so that clinical use thereof is strictly restricted (van Kammen, D. P. (Compiled under Supervision by Murasaki Mitsuroh), “RINSHOU SEISHIN YAKURI”, Vol. 4, pp 483-492 (2001)).
Accordingly what is needed are new compositions useful for treating mood disorders, particularly, depression and major depressive disorder, which are efficacious and do not cause the deleterious side effects associated with prior art compounds.